The plugin seems to be doing something weird for me, or it could well just be me doing something wrong....

I have 3 separate 'panels' in Sketchup, stacked to use up a 20x20cm sheet, however the plugin seems to stack them end on, creating a panel that is 6cm x 60cm - which obviously isn't going to work very well on a 20x20 sheet when Seeed try to cut it.